


Westermarck, Refuted

by etothepii



Series: Westermarck [1]
Category: Sherlock (TV)
Language: English
Status: Completed
Published: 2011-02-06
Updated: 2011-02-06
Packaged: 2017-10-17 08:40:37
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,388
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/174977
Author URL: https://archiveofourown.org/users/etothepii/pseuds/etothepii
Summary: <blockquote class="userstuff">
              <p>He says, "It's good to see you, Sherlock," and the sound of his deep voice wrapping itself familiarly around the vowels of your name makes something inside you perk up and take notice, because that's how he's always said your name, but it's never sounded like <em>that</em> before.</p>
            </blockquote>





	Westermarck, Refuted

**Author's Note:**

> The sex happens when Sherlock is 17 and Mycroft is 24. Contains incest and dubcon.

You are thirteen when you first notice it -- that sometimes you want to touch, that sometimes you don't want to be off to the side while the other children play their boring, stupid games. There are people, and sometimes they're not the same as everyone else; they're interesting, they're fascinating, you want to be near them and touch them and have something from them that is special, that can belong to you and only you.

You know what it is, of course -- you read voraciously, and see the things that no one expects you to understand. A crush. Infatuation. Romance -- if children are even capable of that, and you know they aren't. You know _you_ aren't.

So you ignore it, because it doesn't matter. Because it feels nice to like someone (because it makes something inside you flutter happily to hear his voice, even if he's not speaking to you), but you know that's as far as it'll go.

It goes away, in time, and sometimes it comes back as someone else, someone you've never noticed before but who's suddenly become _interesting_. You never act on it.

You're fourteen when you realize that you notice _him_ too. He's not-quite twenty-one yet, and still in uni. You've never noticed him like this until he smiles at you and gives you a perfunctory hug to make Mummy pleased. He smells like cigarettes (faintly, hasn't smoked for days but the scent's already sunk into the collar of his coat) and aftershave.

He says, "It's good to see you, Sherlock," and the sound of his deep voice wrapping itself familiarly around the vowels of your name makes something inside you perk up and take notice, because that's how he's always said your name, but it's never sounded like _that_ before.

 _Fascinating_.

You hover around the open door to his room while he unpacks his things. "You're not as fat as you used to be," you blurt out, when he strips off his shirt to change for dinner. Because he isn't -- you've seen him undressed before, and he's always been soft and round and unassuming (except for his mind, which is sharper and more dangerous than even your own).

But now there are muscles in his arms and the layer of padding around his upper body is diminished, and you feel -- something. The urge, the barely-familiar wanting. You want to run your hands over his body and press your face against his skin and memorize everything that's changed since you've seen him last.

"Obviously," he says, not looking at you. You're glad he's not looking at you, because if he looked at you, saw the way your eyes trailed over his body, lingering, he'd _know_. He takes off his trousers. Your face flushes and your heart skips a beat, and suddenly you feel overwarm, even though logically, _logically_ you know he's nothing much to look at.

You look away, staring fixedly at the door. When you look back again, having finally willed the excess of blood from your cheeks, he's fully dressed again -- in nice clothes, closely-tailored things that make your mouth dry, and he's _looking_ at you.

He knows, you realize abruptly, and your heart begins to pound. You think it's fear, but there's something else there too, underneath it, a sort of wild anticipation, because he's the only one who's ever known, and you don't know what happens next.

He gives you a wide berth when he steps around you to get through the door. He doesn't touch you at all, after that, and you're as bitterly disappointed as you are breathlessly grateful that he never brings it up to your mother.

You expect it to go away, because it's always gone away in the past. But the thing is, you've always liked minds more than you've liked appearances, and above all, Mycroft has a brilliant mind. He's _smarter_ than you, even if he doesn't always show it, even though he's infinitely better at blending in and seeming normal than you'll ever be.

It doesn't go away.

He avoids you, and ignores you, and manages to do it so skillfully that _you_ are the one who gets in trouble for it. You'd have expected that to make you angry, but what you feel instead is _admiration_.

When you touch yourself, you imagine his hands on your prick and his weight pressing you into the bed. You know what he sounds like when he gasps, and you know how he looks when he's flushed, and you distort the images and memories you have of him until in your thoughts he's gasping in _pleasure_ and flushed with _desire_.

You come all over your fingers, and when you lick the semen from the back of your hand, you pretend it's his.

The next morning, he knows what you did, of course. He flushes when he sees you. Your mother doesn't notice, but then, she doesn't notice much of anything. You should be ashamed, you think, because you know it's wrong. It's supposed to be carved into your upbringing (into your very nature) to not want this, to not want _him_.

It doesn't go away.

You turn fifteen. Your voice drops, you're always hungry, and you manage to knock no fewer than three antique vases onto the ground by accident. You know you'll one day be tall and graceful (you've done the analysis on the size of your hands and feet) but right now you are a clumsy mass of elbows and knees and adolescence.

Girls notice you now. They look up at you, they giggle, and they smile, even when you ignore them. _Boring_.

After Mycroft graduates, he comes home for a month to visit. He gives your mother a hug and allows her to kiss both cheeks. He catches sight of you over her shoulder a mere second before your mother turns and beckons you over to greet him.

You hug him and it's awkward, because you're both tense. You're hyper-aware that he hasn't shaved yet today, that he smokes still, that he showered in the morning and his shampoo smells nice but doesn't completely mask his natural scent. You're only a few inches shorter than him now and don't have any trouble looking him in the eye.

"You've grown," he says for your mother's benefit, because you know he dislikes stating the obvious nearly as much as you do.

"Among other things," you agree, and you don't miss the way his eyes widen slightly when he hears the way your voice has changed. You have a man's voice now, low and deep and smooth. You wonder if he likes it.

He steals glances at you during dinner -- he looks at your hands, and your face. You shave regularly now, though not every day. You're sure he's already figured out how often, how long you've been doing so (based on the small cuts you accidentally give yourself), and which brand of aftershave you use. You toy with the fork in your hand, letting your thumb rub against the handle, and he looks away sharply.

You don't think about him much when he's away, so you've forgotten what it feels like to _want_ so badly. You don't feel this way about anyone else, and every time he licks his lips or shrugs out of his jacket or pads down the hall in bare feet, you're hit with a dizzy rush of _hunger_.

So, you do what only makes sense, and pick the lock on his bedroom door.

Mycroft is asleep when you join him under the covers. He stirs when you press your cold feet against his bare calves. "Sherlock?" he asks sleepily, and puts an arm around your shoulders, because the last time you'd crawled into his bed, you'd been eight and your father had been dead for not yet two days. "What's the matter? Did you have a nightmare?"

"No," you say, and give in to the urge you've been trying to ignore for over a year now. You're not sure how this is done (you've seen other people do it of course, but that's really not the same at all), but you wrap an arm around his waist and press your mouth, clumsily, against his.

Mycroft doesn't kiss you back, but he groans when you move your mouth lower. The sound sends an electric thrill of arousal to your groin. You press yourself closer against his body.

He stops you. "Sherlock," he says, and pushes you away. "What are you doing?" His voice is not-quite-steady.

"Obvious," you say, and press your hands against his chest. You rarely touch people, but you want to touch _him_.

" _No_ ," he says firmly. "We can't. You're fifteen. We're _brothers_. Brothers don't do this, Sherlock." He keeps saying your name, like if you hear it enough you'll remember who you are. As if you've forgotten.

"But I want you," you say, and hook your leg over his. "More than I've wanted anyone else. And you want me too, Mycroft, I see it when you look at me." Because you have. Because he's been looking at you all night when he thought you weren't paying attention. Because he said _you're fifteen_ , and _we're brothers_ , but didn't say _I don't want to_.

Because he's hard right now, pressed against your thigh.

He shudders when you press your palm against his prick, and he makes a half-aborted thrust against your hand. His fingers drag over your chest, catching on the buttons of your shirt (you dressed nicely because you knew he'd come home today, and it'd paid off when he'd stared at the way you'd left the top two buttons open), using enough pressure that you know he wants to touch you too.

The next thing you know, you're on the floor. Your elbow hurts from the landing. He's pushed you out of bed.

"I said no," Mycroft says firmly, and turns his back. "Get out."

You leave and spend two years pretending it never happened.

  
You are seventeen when you get tired of pretending -- seventeen and going to uni in Autumn. You no longer look half-grown, and the gap between seventeen and twenty-four is not as dramatic as the one between fifteen and twenty-two. You've traded no more than several-dozen words with him over the last two years, but you know he's barely changed at all.

This time, you knock first. When you open his door, he's already awake, sitting up in his bed. You close the door behind you and say, "I don't want to be a virgin when I go to uni."

The curtains are drawn and your eyes haven't adjusted to the dark yet. You can't read his expression when he shifts and says, "And you want me to take care of it for you." His voice is perfectly even. "I already said no."

You start undoing the buttons of your shirt, and move closer. "You said no two years ago. I've grown since then. I'm not a boy anymore. As you've noticed," you add meanly, because you can feel his eyes on you like a near-physical weight. The tip of his tongue darts out to wet his lips when you hook your thumbs into your trousers to push them down.

"We can't," Mycroft says, but his resolve has been weakening with each article of clothing dropped on the floor. "You're not even of age."

This is true, so you don't bother to dignify that with a response. You step out of your trousers, then pull down your pants as well, and he makes a _noise_ again, the sort of unconscious, hungry noise you've been fantasizing about for years.

This time, he doesn't push you to the floor when you crawl into the bed with him. "If you don't," you threaten, "I'll find someone else who will." He knows you mean a stranger, someone who would be rough and masculine and who will probably hurt you (you wouldn't mind, because it'd be different, and you love it when things are different).

You're not bluffing, and he knows you aren't.

You can tell when he capitulates, because something -- some tension inside him, goes away, neatly boxed and hidden away in the recesses of his mind. "Alright. Fine," he says, and puts his hand on your bare waist. The touch sends a rush of blood to your groin. "If you're dead set on having your way, I'll show you."

You kiss him eagerly, clumsily. Your noses bump together, and then your teeth, until he cups the nape of your neck with a large palm. "Let me, I'll show you," he says patiently, and teaches you with his lips and tongue how to slow down and take your time, sweeping his tongue through your mouth with broad strokes.

It's different than the last time. There's no hesitation anymore, and soon you find yourself on your back, your brother between your legs. He's bigger than you -- broader around the shoulders, muscled and with a layer of padding, and he looms over you. "Sherlock," he breathes, and wraps his hand around your prick.

Only two strokes -- two firm, confident, _glorious_ strokes, and you're coming messily over his hand, twisting and gasping and realizing belatedly that he's watching your face while it happens. You turn your face away, embarrassed.

When he doesn't say anything, you sneak a glance at him. He's not looking at you -- or, he is, but he doesn't see you, he sees your body. His expression is closed and unreadable, but you know he's thinking -- about you, about what he wants to do, and it sends a thrill of anticipation of up your spine. When he notices your attention, he wipes his hand clean on your belly.

"Done?" he asks, and starts to climb off you, to give you space. You pull him back down. You're not done yet.

"You want to fuck me," you say, to hear the sharp breath he takes, and to feel the way his hips jerk, slicking his erection against the inside of your thigh. "Don't deny it, I know you want to. Do it."

"Are you sure?" he asks, but he doesn't wait for a response, just leans over the edge of the bed to get at his book bag, pawing through it with clumsy hands.

"What are you looking for?" You ask curiously, but his shoulders block your view. His back is freckled (you know this already), and you trace each dot with your tongue, drawing a meaningless pattern. "Don't use a condom." He's your first, and you already know _he_ isn't stupid enough to have unprotected sex with anyone (anyone who isn't you).

"Lubricant," he replies, and shows you the small bottle.

You take it curiously, turning it over in your hands. Lubricant, of course -- you know the theory behind men having sex with men, and you know what anal sex _is_. But the rest of your knowledge is schoolboy gossip and dirty magazines. Sometimes it's hard to tell what's the truth and what isn't.

He takes off his pants, freeing his prick. When he holds out his hand for the bottle you're still holding, it hits you abruptly that you have no idea what you're doing. Because he's large, larger than you'd imagined, and suddenly you find yourself realizing with just a hint of hysteria that he intends to be _inside_ you, and it's going to hurt. And you can't stop, because you've spent three years wanting him, and this will be your only chance to have him, and if you say no now, he'll never say yes again.

You are quietly panicking when you register his hand squeezing your thigh. His other hand plucks the lubricant from your grip. "It's alright Sherlock," he murmurs soothingly. He's moved close enough for you to feel his body heat, and it comforts you. "I've done this before, just trust me. I won't hurt you, I promise. Do you trust me?" You nod, and he says, "Close your eyes. Relax."

You close your eyes and lay back. After a few seconds, where you hear the click of the bottle's cap opening and closing, you feel the press of a cool, slick finger beneath your testicles, circling your hole. He kisses the side of your upraised knee.

"Do you want me to stop?"

"Don't be stupid," you snap, and he laughs.

It doesn't hurt when he pushes one finger inside you, but it definitely feels foreign, and you shift uncomfortably. You aren't sure if you like it. He adds a second finger, and you know he's being careful, as gentle as he can, but the stretch of your muscles around him hurts. He puts his palm on your belly when you start to squirm.

"Don't move," he says, fucking you slowly with his fingers. "Hold still."

You open your eyes, and he's looking down, lips parted -- staring at his fingers inside you, at the way your bodies are joined together. You do the calculations and say, "If you add another finger, you'll still have less girth compared to your prick."

Mycroft reaches for the bottle again, withdrawing his fingers. "I know what I'm doing. Would you rather be on your back, or your hands and knees? The latter will be more comfortable for you, but the former is considered more intimate."

You turn over and brace yourself on your hands and knees. Three fingers, and it hurts as he pushes in, but you clench your jaw and refuse to let on about the pain. You know he figures it out, though, because he drops a tender kiss to the small of your back.

"I'm going to do it now," he says, still using a careful, measured tone you've never heard before. He's never been this gentle with you before -- you wonder if he talks to all his lovers like this, or if it's just you. "Tell me if it becomes too much."

It hurts. It _hurts_. It hurts so much. It feels like you're being split apart. You dig your fingernails into the bedsheets and grit your teeth, determined not to back down.

Mycroft stops, and a warm hand strokes your back. "Relax," he says again. "You're too tense. Push into it," he coaxes, and then, in a soft, idle voice that cuts straight to some place inside you that you never knew existed, he continues, "You're so gorgeous like this, Sherlock. Spread out and beneath me and I wish I'd never thought of you like this but now that I have I can't stop. You're beautiful and you're _mine_ and sometimes I wish I was better for you, not like this. I wish --"

"Keep going," you say. You press backwards, taking a little bit more of his length into you, because you want him to stop talking -- you _need_ him to stop talking, because he's Mycroft, and he's your big brother, and he's supposed to be unstoppable. He's supposed to know everything and be able to do anything, and this hint of something different scares you deep in your chest.

Because he's more than you'll ever be (you know this, even if you'll never admit it to anyone but yourself), and if he can't be invulnerable, then what does that say about you?

You've adjusted more to the size of his prick inside you, and it hurts less when he moves again, pushing inside you until he's in all the way, your bodies flush against each other. He bends over, until you can feel his chest against your back.

"Okay?" he asks, voice strained with the effort of holding still.

You nod against the pillow, and he begins to move. It's alright; it hurts still but not too badly to bear, but it's good, because you like the press of his body against yours, and the sound of his breathing as it gradually speeds up. The sharp pang of pleasure takes you completely by surprise -- prostate, you know, pleasurable for some but not all men, and apparently you're in the former group because the shock of it has you groaning.

Mycroft makes a pleased noise behind you. He learns quickly, as quickly as you do, and now that he's found the right angle, he does it again and then _again_ , each deliberate, careful thrust sending a burst of pleasure through your body until you're moaning softly.

You're not surprised to note that you're hard again, and you take yourself in hand, stroking with the rhythm of Mycroft's thrusts. "Harder," you say. "Faster."

He obeys, pounding into you, and your entire world narrows down to this moment. To only this, this bed and this night and yourself and your brother, wringing pleasure from each other's bodies. He comes before you do -- grunting inelegantly and going still as his orgasm hits. His prick pulses inside you, _comes_ inside you. When he withdraws, he collapses sweaty and spent next to you on the bed.

Normally you'd be disgusted at the sweat on his face and he way he's panting, but right now it just pushes you closer to the edge. You crowd up against him eagerly, devouring his mouth. He grabs your wrist when you try to finish.

"I can," he says, so you open your hand and let him push your wrist against the sheets. "Be still."

He drags his lips down your body -- avoiding the sticky, drying patch of semen left from when you'd first come. He skips past your hard prick and keeps going, mouthing lower.

"Sherlock," he says. He sucks a bruise onto the inside of your thigh -- and you hadn't thought of that, that he can mark you anywhere that won't be visible later, anywhere Mummy won't see. ( _Yes,_ you think. _Yes_.) "Sherlock, I'm going to suck you, and I'm going to let you come in my mouth."

" _Fuck_ ," you breathe. "Please, yes."

The sudden wet heat of his mouth has you bucking your hips, thrusting deeper, and you're surprised when he makes a choking noise and pins your hips to the bed with his forearm. It's followed by a thrill of pleasure, because you'd _enjoyed_ that -- enjoyed having Mycroft choking on your cock because it was too much for him.

He finishes you easily -- builds the heat and wetness and suction so quickly that you're caught by surprise when you come, spilling into his mouth, just as he'd promised. His throat works when he swallows. "You need to shower," he says, touching the marks on your body -- the one on your thigh, and the hand-shaped bruises on your hips. "Don't get caught."

  
You don't get caught.

That is, you don't get caught _then_.

Because now that you've done it once, you want to do it again. Mycroft's never been especially good at denying you, which is why you are on your knees in the grass, his cock down your throat (you are better at suppressing your gag reflex than he is) and his hands fisted in your hair when your mother turns around the corner and catches you both.

There is a lot of screaming and crying on her part, and yelling on yours (you don't remember exactly what you said -- probably something about how stupid taboos are, and how worthless the Westermarck effect is, and how you're a homosexual and Mycroft's a homosexual and so there's hardly any reason against what they're doing).

Mycroft grabs your arm and sends you to your room, like you're a _child_. Ironic, considering you can still taste him in your mouth. But you go anyways, because you have no idea what you're supposed to do instead.

Getting caught had never been part of the plan.

  
"We can't do this again," he says to you later that night, hours after you have returned to your room and started reading. His eyes are rimmed with red. He's been crying. "We can't. It upsets Mummy, and you know she has a fragile heart."

The first thought that comes to mind is, _I don't care_ , which aside from being technically untrue, is also certain to upset your brother. "She doesn't have to know," you say instead, because you don't want to imagine losing this. "We're both clever enough to keep it secret from her."

Your brother's mouth twists. "That's not the point," he says. "It's _wrong_. It's criminal, what I did to you. And you _know_ I can't afford something like this when I'm going into politics."

His career. Of course.

Something inside you goes cold and brittle. "Of course," you snap. "You wouldn't do anything to jeopardize your position in the government, would you? Planning on being prime minister by the time you're thirty?"

"Don't be churlish at me, Sherlock. This isn't up for discussion. _It was a mistake_ , and it won't be happening again."

"It didn't look very much like a mistake, not from here. You wanted to -- I'm not blind, you've been watching me for years, and you were _eager_ when I finally offered myself to you. 'Do you trust me?'" you parrot meanly, just to see him flinch. "'On your back, or on hands and knees?' 'I'm going to suck you, _Sherlock_ , and you're going to come in my mouth.'

Do you really think we'll never do it again? Come on, it's obvious you've got barely any self-control. Can you honestly say you'll never hold me down and spread me open and lick me clean and --"

You're stunned silent by the sharp, sudden crack of his palm across your cheek, and the rest of your words die in your mouth. Mycroft's livid, and twin spots of anger burning in his cheeks as he hisses, "Why do you have to be so _fucking_ heartless all the time? Don't you care about anything at all? No, of course you don't. You don't care a thing about me or Mummy, just about yourself and what you want. Fine. Destroy this family if it pleases you, but when you do, I want no part in it."

He storms out, slamming the door shut behind him. He leaves the next day.

You don't see him again for years.

By then, you're far enough down the path of destroying your family through recreational drug use and he's done enough unspeakable things in the name of the greater good that the addition of incest seems only a minor sin.


End file.
